1. Field of the Invention
This invention relates to large area semiconductor power diodes and a temperature gradient zone melting process for making the same.
2. Description of the Prior Art
Heretofore, commercial seimconductor diodes have been made by diffusion, alloying or epitaxial growth techniques. All such processes involve procedures wherein the optimum physical characteristics of the diodes are never achieved. Procedures are such that the introduction of contaminants inherent with the process techniques practiced degrade the physical characteristics of the diodes manufactured.
W. G. Pfann in his U.S. Pat. No. 2,813,048, teaches thermal gradient zone melting techniques for making various semiconductor devices. However, Pfann's devices had too many deficiencies to enable the process to be employed commercially.
It is desirable to have large area power diodes made from commercially available semiconductor wafers provided a reliable efficient method could be developed to make the diodes.
An object of this invention is to provide a new and improved process for making a large area semiconductor power device, the structure of which overcomes the deficiencies of the prior art.
Another object of this invention is to provide a new and improved process for making a large area semiconductor power diode which has maximum theoretical breakdown voltage as determined by the materials embodied therein.
Another object of this invention is to provide a new and improved process for making a large area semiconductor power device embodying a sharper P-N junction profile than any P-N junctions in prior art devices.
A further object of this invention is to provide a new and improved process for making a large area semiconductor power diode which has a faster recovery time and better switching characteristics than the prior art power diode devices.
A still further object of this invention is to provide a new and improved temperature gradient zone melting process to make new and improved large area semiconductor power devices which include regions of recrystallized semiconductor material which are substantially free of defects such, for example, as metallic inclusions.
Other objects of this invention will, in part, be obvious and will, in part, appear hereinafter.